The subject matter disclosed herein relates to smoke detectors and, more particularly, to photo-electric smoke detectors using multiple light emitters and receivers.
A smoke detector is a device that detects smoke and issues an alarm. A photo-electric smoke detector, meanwhile, is a type of smoke detector that works based on light reflection principals and generally includes a light emitter, a light receiver and an optic chamber. When there is no smoke in the optic chamber and the optic chamber is empty or mostly empty, the light receiver typically receives a small amount of light reflected from chamber surfaces. On the other hand, when smoke is present in the optic chamber, the light receiver receives more light due to that light being reflected from the smoke particles. When an amount of the received light exceeds a predetermined level, an alarm is triggered.
As operated in this manner, photo-electric smoke detectors are not able to discriminate between large-size non-smoke particles, such as steam clouds, dust clouds, etc., and small-size non-smoke particles that are generated by certain types of cooking scenarios. That is, photo-electric smoke detectors are not capable of determining when small-size non-smoke particles are generated by safe activities, such as broiling hamburgers, toasting bread, etc., and thus permit false alarms to be triggered.
As a result, photo-electric smoke detectors will not pass upcoming, new Underwriter Laboratories (UL) 217-8 and 268-7 standards which require that smoke detectors and photo-electric smoke detectors, in particular, be configured to not sound an alarm during “broiling hamburger” tests.